Extraction of Algal Lipids and Their Analysis by HPLC and Mass Spectrometry

Algae are a promising source of biofuel but claims about their lipid content can be ambiguous because extraction methods vary and lipid quantitation often does not distinguish between particular lipid classes. Here we compared methods for the extraction of algal lipids and showed that 2-ethoxyethanol (2-EE) provides superior lipid recovery (> 150-200 %) compared to other common extraction solvents such as chloroform:methanol or hexane. Extractions of wet and dry algal biomass showed that 2-EE was more effective at extracting lipids from wet rather than dried algal pellets. To analyze lipid content we used normal-phase HPLC with parallel quantitation by an evaporative light scattering detector and a mass spectrometer. Analysis of crude lipid extracts showed that all major lipid classes could be identified and quantified and revealed a surprisingly large amount of saturated hydrocarbons (HC). This HC fraction was isolated from extracts of bioreactor-grown algae and further analyzed by HPLC/MS, NMR, and GC/MS. The results showed that the sample consisted of a mixture of saturated, straight- and branched-chain HC of different chain lengths. These algal HC could represent an alternative biofuel to triacylglycerols (TAG) that could feed directly into the current petroleum infrastructure.